/*
 * Copyright 2002-2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.transaction.reactive;

import java.util.Deque;

import org.springframework.transaction.NoTransactionException;

/**
 * Mutable holder for reactive transaction {@link TransactionContext contexts}.
 * This holder keeps references to individual {@link TransactionContext}s.
 *
 * @author Mark Paluch
 * @author Juergen Hoeller
 * @see TransactionContext
 * @since 5.2
 */
final class TransactionContextHolder {

    private final Deque<TransactionContext> transactionStack;


    TransactionContextHolder(Deque<TransactionContext> transactionStack) {
        this.transactionStack = transactionStack;
    }


    /**
     * Return the current {@link TransactionContext}.
     *
     * @throws NoTransactionException if no transaction is ongoing
     */
    TransactionContext currentContext() {
        TransactionContext context = this.transactionStack.peek();
        if (context == null) {
            throw new NoTransactionException("No transaction in context");
        }
        return context;
    }

    /**
     * Create a new {@link TransactionContext}.
     */
    TransactionContext createContext() {
        TransactionContext context = this.transactionStack.peek();
        if (context != null) {
            context = new TransactionContext(context);
        } else {
            context = new TransactionContext();
        }
        this.transactionStack.push(context);
        return context;
    }

    /**
     * Check whether the holder has a {@link TransactionContext}.
     *
     * @return {@literal true} if a {@link TransactionContext} is associated
     */
    boolean hasContext() {
        return !this.transactionStack.isEmpty();
    }

}
